The invention relates to a positive displacement supercharger for the compression of air using the exhaust gases of an internal combustion engine, and more specifically a piston engine. The supercharger according to this invention has at least one exhaust gas chamber and at least one air chamber, each of said chambers being able to be varied in its volume by way of a moving, chamber partition, said chambers each having an inlet and an outlet.
Positive displacement superchargers driven by exhaust gas are known as a theoretical possibility. However the utilization of the exhaust gas energy periodically leaving one of the engine cylinders poses difficulties in many cases.
In the case of four cylinder engines the exhaust gas pulses mutually hinder each other so that, with an increase in the number of cylinders, there is less and less available energy gradient for driving the partition by means of the natural exhaust gas pulses. A similar effect is to be noted at a high engine speed.
For a number of different methods--more specifically those that have been recently developed--it is beneficial or even unavoidable to use a positive displacement supercharger. For this reason there is a need for general purpose positive displacement superchargers, which may be used for engines having a large number of cylinders or a high rated engine speed.
The object of the present invention is to so develop a positive displacement supercharger of the type described above that may be used for a number of different applications, more specially with engines with a large number of cylinders or a high rated speed for producing novel methods and systems operating to save energy.
In order to effect this purpose the supercharger according to this invention has partitions that are ganged together for joint motion. There is then the possibility of designing the supercharger with exhaust gas chambers that are to be acted upon by exhaust gas in opposite directions, the engine cylinders used for operation of the supercharger by supplying it with exhaust gas being associated in two groups with the two exhaust gas chambers. The outcome of this design is that the frequency of the pressure pulse taking effect in one exhaust gas chamber is halved and the available energy gradient is correspondingly improved, more specially as regards the utilization of the high energy natural exhaust pulses of IC engines. In keeping with one specially useful form of the invention, the supercharger has two exhaust gas chambers, that are placed on the two sides of a partition and two air chambers which are placed on two sides of another partition. Then it is possible to be certain of a very efficient separation of the exhaust gas sections from the air sections.
In keeping with a further useful development of the invention, the partitions are fitted with a guide rod running out of the chambers to a point at which it is guided in the direction of motion of the partitions, the guide play and the guided length being of such a size that a partition designed in the form of a piston may be moved in its chamber without making contact with the chamber walls. Therefore, losses through friction may be kept down to a minimum, more specially seeing that the separation of the exhaust gas chambers from the air chamber or chamber cuts out any danger of a mixing together of the exhaust gas and the supercharged air, if the seal of the chambers on the two sides of the piston is produced by having a suitably narrow clearance between the piston and the chamber inner face next thereto.
The partitions that are ganged together so that they are moved jointly may be linked by mechanical means or their motion may be caused to be in step by way of a synchronizing means.
In keeping with a further useful design, the acting faces of the partition facing into the supercharging air chamber and into the exhaust gas chamber are different in area. If the acting face on the exhaust gas side is larger, then a high supercharging pressure may be produced; if the acting face on the supercharged air side is larger, then a large volumetric air pumping rate will be possible.
In keeping with a further useful development of the invention, two partitions are ganged together for motion in unison by joining them together by way of a means which is adapted to transmit the motion of the one partition to the other one in the opposite direction so that there is a balancing of inertial forces. The device for transmission of motion may be mechanical or hydraulic in its operation.
As part of a specially beneficial further development of the invention, the supercharger has two exhaust gas chambers and two supercharging air chambers, the outlet of the first supercharging air chamber being joined up via a cooler with the inlet of the second supercharging air chamber and having its outlet joined with the inlet of the engine cylinder that is to be supercharged. In this case the air that is firstly compressed may expand and perform work that is absorbed by the supercharger and at the same time the supercharging air cooled by cooling and expansion will improve the engine performance.
In the event of two exhaust gas chambers not being enough for efficient supercharger operation, each exhaust gas outlet may be fitted with a choke, that if desired may be one that is adjustable with respect to the pressure and/or the time of the choking effect to optimize the exhaust gas pulses. For the same purpose it is furthermore possible for the exhaust gas inlet and/or outlet to be fitted with a controlled valve.
A further development of the invention consists in that an exhaust gas collecting means is joined with the exhaust gas inlet on the upstream side thereof and the exhaust gas side of the supercharger is fitted with a pulse generator. This stroke control may be on the basis of an automatic controller, that for example takes into account the operating characteristics and data of the system as a whole. The stroke control on the exhaust gas side of the supercharger may however be triggered by the natural exhaust gas pulses of the engine or by a connection with the engine.
Further useful developments of the invention will be seen from the dependent claims taken in conjunction with the account now to be given.
Using the following account, working examples of the invention to be seen in the figures will now be explained.